Just have him buy the game, and when he registers his account in the game it will ask if anyone referred him, have him put YOUR NAME in that box and if it asks for a friends email as well, have him enter the email there. Hope this helps!

This is a rare issue with our server`s email, about 4%-7% don`t get our emails, we are tried looking into it, but without switching our email provider (which is too big of a step), we can`t fix it. Sorry.

But as somebody stated above - you can just point the game to them in our own store or on Steam (free Dragon if from our own store, plus it`s the same Steam copy)